add first basic program structure

Makefile

@@ -0,0 +1,7 @@
+.PHONY: build test
+
+build:
+	go build -o build/
+
+test:
+	go test -v ./...

go.mod

@@ -0,0 +1,5 @@
+module git.faercol.me/monitoring/heartbeat-server
+
+go 1.16
+
+require github.com/sirupsen/logrus v1.9.0

go.sum

@@ -0,0 +1,15 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.9.0 h1:trlNQbNUG3OdDrDil03MCb1H2o9nJ1x4/5LYw7byDE0=
+github.com/sirupsen/logrus v1.9.0/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 h1:0A+M6Uqn+Eje4kHMK80dtF3JCXC4ykBgQG4Fe06QRhQ=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

main.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"context"
+
+	"git.faercol.me/monitoring/heartbeat-server/server"
+	"github.com/sirupsen/logrus"
+)
+
+func main() {
+	addr := "localhost:9000"
+	logger := logrus.New()
+
+	srv, err := server.New(addr, logger)
+	if err != nil {
+		logger.Fatalf("Failed to create HTTP server: %s", err.Error())
+	}
+
+	srv.Run(context.Background())
+}

server/server.go

@@ -0,0 +1,59 @@
+package server
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/http"
+
+	"github.com/sirupsen/logrus"
+)
+
+type Server struct {
+	ctx      context.Context
+	cancel   context.CancelFunc
+	httpSrv  *http.Server
+	listener net.Listener
+	handler  *http.ServeMux
+	logger   *logrus.Logger
+}
+
+func (s *Server) initMux() {
+	s.handler.HandleFunc("/", s.heartbeatHandler)
+}
+
+func (s *Server) heartbeatHandler(w http.ResponseWriter, r *http.Request) {
+	remoteHost, _, err := net.SplitHostPort(r.RemoteAddr)
+	if err != nil {
+		s.logger.Warnf("Unexpected remote address %s: %q", r.RemoteAddr, err.Error())
+	} else {
+		s.logger.Infof("Received a heartbeat query from %s", remoteHost)
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
+func (s *Server) Run(ctx context.Context) {
+	s.ctx, s.cancel = context.WithCancel(ctx)
+	s.initMux()
+	if err := s.httpSrv.Serve(s.listener); err != nil {
+		s.logger.Errorf("Failed to serve HTTP server: %s", err.Error())
+	}
+}
+
+func New(addr string, logger *logrus.Logger) (*Server, error) {
+	m := http.NewServeMux()
+	l, err := net.Listen("tcp", addr)
+	if err != nil {
+		return nil, fmt.Errorf("failed to setup listener on addr %q: %w", addr, err)
+	}
+
+	return &Server{
+		ctx: context.TODO(),
+		httpSrv: &http.Server{
+			Handler: m,
+		},
+		handler:  m,
+		listener: l,
+		logger:   logger,
+	}, nil
+}